Thread severing device for severing the looper and needle threads on double chain stitch sewing machines



3, 69 D. SCHOPF 3,424,117 THREAD SEVERING DEVICE FOR SEVERING THE LOOPERAND NEEDLE THREADS ON DOUBLE CHAIN STITCH SEWING MACHINES Filed May 6,1966 Sheet 0f 5 I 6 F164 V f INVENTOR DIETER SCHOPFY Wm ATTORNEY5 22% BY6%, WW R Jan. 28, 1969 SCHOPF 7 3,424,] l 7 THREAD SEVERING DE E FORSEVERING THE'LOOPER AND NEEDLE T ADS 0N DOUBLE CHAIN STITCH SEWINGMACHINES Filed May 6, 1966 Z of 5 Sheet INVENTOR DIETER SCHOPF BY "W WAE 3,424,111 HE LOOPER AIN D DEVICE AND OFF

5 RING T BLE HIN Jan. 28, 1969 S THREAD SEVERING F NEE E EADS ON SEWINGMAC I Sheet Filed May 6. 1966 IFIG.5b

INVENTOR DIETER SCHOPF 4942,, PM; W X

Jan. 28, 1969 D. SCHOPF 3,424,117

- THREAD SEVERING DEVICE FOR SEVERING THE LOOPER AND NEEDLE THREADS 0NDOUBLE CHAIN STITCH SEWING MACHINES Filed May 6, 1966 Sheet 4 of 5IFIIG.6

INVENTOR 0| ETER SCHOPF 4W2, @012, mm @mm/ ATTORNEYS Jan. 28, 1969 D.SCHOPF' THREAD SEVERING DEVICE FOR SEVERING THE LOOPER AND NEEDLETHREADS ON DOUBLE. CHAIN STITCH SEWING MACHINES Sheet 2 of 5 Filed May6, 1966 INVENTOR .DIETER SCHOPF United States Patent U.S. Cl. 112252 23Claims Int. Cl. D05b 65/02 ABSTRACT OF THE DISCLOSURE A thread severingdevice for double chain stitch sewing machines is disclosed herein. Thesevering device includes a thread catcher movable between the threadcarrying looper blade and the stitching plate for catching the threadand drawing the thread into clamping engagement with clamping means andinto cutting engagement with cutting means whereby the looper thread iscut and clamped at a predetermined point and whereby the needle threadmay be cut and released at said point. The cutting and clamping meansmay be movable to and retractible from the predetermined point andcontrol provisions are disclosed for controlling the operation of thesevering device and for drawing off a predetermined amount of looper andneedle thread upon actuation of the severing device such that a newsewing operation may be begun.

The invention concerns a thread severing device embodied in double chainstitch sewing machines, wherein the needle thread loop lies around theblade of the thread carrying looper when the needle is in high position.

In such double chain stitch sewing machines heretofore various threadcutting devices have become known by use of which the thread chain canbe separated at the end of one sewing element. However, such devices aswill permit the separation of the threads whenever the seam ends insidethe material have not been known.

Heretofore, in known practices, when the seam ends in the sewingmaterial, it has been customary for the seamstress to turn the handwheel opposite to the normal running direction in order to throw off theloop of the needle thread from the looper blade, whereupon theseamstress would pull away the sewing material from below the pressurefoot which had been lifted and would separate the threads with a pair ofscissors or a cutting knife.

In order to simplify the turning of the hand wheel in the oppositedirection, disclosure has also been made of a motor which carries outthis turning backward after the stopping of the sewing machine.

In either case, however, the severing of the threads in the case ofdouble chain stitch sewing machines is awkward and time consuming,whenever the seam ends within the material, and a relatively large lossof thread will occur. It is true, that it has been known in the case ofbuttonhole machines, which use a double chain stitch, to separate thethreads below the stitching plate. However, in the case of these sewingmachines, the development of the stitch takes place in a differentmanner than it does in the case of normal double chain stitch sewingmachines, where the loop of the needle thread in the case of the highposition of the needle lies around the blade of the thread carryinglooper. Besides, in the case of these buttonhole sewing machines, theseparation of the thread has been controlled automatically with thesewing process, whereas in the case of a normal sewing machine thecourse of the work process is controlled at will. For these 3,424,117Patented Jan. 28, 1969 reasons, it is not possible to transfer thethread severing equipment of buttonhole sewing machines to normal doublechain stitch sewing machines.

The present invention serves the purpose of cutting off the threads ondouble chain stitch sewing machines wherein the loop of the needlethread in the high position of the needle lies around the blade of thethread carrying looper, whenever the seam ends in the material beingsewn, and is based on the problem of creating a thread severing deviceby which the threads can be cut off closely below the material and beheld in a manner, which assures that a faultless formation of the stitchwill be guaranteed upon restarting of the sewing machine.

This problem essentially is solved by providing a thread seizing deviceor thread catcher which moves between the looper blade and the stitchingplate, and will cooperate with a cutting blade and a fiat Elampingspring or spring clip, and whose seizing beak or catcher hook moves on acourse in relation to the looper being in its foremost end position,said course extending within the area of the looper point, across thelooper blade and from there through the path of the needle up to a pointon that side of the path of the needle which faces away from the looper.At the same time, the thread catcher moves preferably between thecutting blade and the clamping spring or clip and has a cutting edgewhich corresponds to the edge of the cutting blade. The clamping springor clip presses the catcher hook against the cutting blade and serves,at the same time, for clamping the threads against the thread catcher,whereby at least the severed looper thread extending to the eye of thelooper is retained by the clip spring in the end position of the catcherhook. Through this design and arrangement of the cooperating elements itbecomes possible to arrange a thread severing device or thread catcherin the limited space between the looper blade and the stitching platewhich catches the looper and the needle threads, cuts them off andretains them in such a position that a faultless stitch formation isinsured when the sewing machine starts up again.

In order to avoid an automatic unraveling of the double chain stitchseam from the direction of the end of the seam, for practical purposesthe cutting blade and the spring clip are movable in relation to thethread catcher, in such a manner that the shearing effect of the cuttingedges takes place a predetermined distance from the path of the needleand the end position of the cutting edges with the cutting edges spacedfrom the upper edge of the stitch hole at a distance approximately twicethe length of the stitch.

Another embodiment of the thread severing device or thread catcherconsists in providing one catcher hook or seizing beak each for theneedle thread and the looper thread, preferably on one common threadcatcher. Through this arrangement it becomes possible to draw out thethreads individually, to cut them off and to clamp them.

In the case of the arrangement'of both seizing beaks or catcher hooks onone thread catcher, the catcher hook for the needle thread has beendisplaced in the direction of movement of the hooks, in such a manner inrelation to the catcher hook for the looper thread that in its pushedout or projected position it will extend between the looper thread andthe needle thread. The novel arrangement is such that only the catcherhook or seizing beak for the looper thread cooperates with the clampingspring or clip, in order to clamp the looper thread in the rest positionof the catcher hook.

Thus, a clamping of the needle thread will be avoided without impairingthe safe clamping of the looper thread. This is particularly importantwhen sewing thin materials,

since a clamped needle thread at the beginning of a seam leads topuckering.

A preferred embodiment of the cutting-off device is characterized by thefact that the spring clip is equipped with a notch, the edge of which isspaced from the free end of the spring clip at a distance that issmaller than the clamping surfaces of the catcher hooks.

Other embodiments consist in this, that the catcher hooks are displacedlaterally in relation to one another in their direction of movement andin that the spring clip covers only the course of movement of thecatcher hook for the looper thread, or else in that that surface of thecatcher hook which faces-the spring clip and which is intended for theneedle thread recedes in relation to the remaining surface of thecatcher hook, or in that the catcher hook for the needle thread has anedge to break the needle thread.

Finally, it is also possible to displace the spring clip with andrelatively to the thread catcher and merely to provide on the springclip a blind catcher hook for the needle thread.

With the above and other objects in view that will hereinafter appear,the nature of the invention will be more clearly understood by referenceto the following detailed description, the appended claims and theseveral views illustrated in the accompanying drawings.

In the drawings:

FIGURE 1 is a front elevation, parts being broken away, showing a doublechain stitch sewing machine embodying the invention.

FIGURE 2 shows a part of the opened machine bed viewed from above.

FIGURE 3 is a perspective view schematically illustrating one form ofthread cutting device embodying the invention, the same being shown inthe swung-in or projected condition.

FIGURE 4 shows the thread cutting device in the retracted position.

FIGURE 5 is an enlarged sectional view showing the end of the seam withthreads cut off and protruding a considerable distance from the fabric.

FIGURE 5 is a view similar to FIGURE 5 with the dangling needle threadpulled in toward the preceding needle thread loop.

FIGURE 6 is a circuit diagram.

FIGURES 7 and 8 are views similar to FIGURES 3 and 4 and showing similarpositions of a modified form of the invention.

In the embodiment of the invention herein disclosed the sewing machinehas a customary housing 1, in which a needle bar 2 carrying a needle 3is guided. The needle bar and needle are driven in the known manner andthe needle operates together with a thread carrying double chain stitchlooper 4. The drive of the machine takes place via a belt pulley 5,which is connected with a known type of transmitter, not shown, whichputs the needle into high position in the stopping position. The needlethread 6 and the looper thread 7 are moved via tension discs 8, 9 andthe customary thread guiding parts to the needle 3 and the looper 4. Aspreader 10 cooperates in the well known manner with the needle 3 andlooper 4 in the formation of stitches, the spreader serving to widen outthe thread triangles during sewing, opposite to the normal sewingdirection.

Additionally, according to the present invention, thread draw-off parts11, 12 have been provided which, preferably, have been adjustablysecured to a shiftable plate 13. These thread drawing-off parts,furthermore, carry disc spacers 14, 15, which are engageable between thetension discs 8 and 9 for deactivating the same. An actuatingelectromagnet 16 is provided for bringing about desired shifting of theplate 13 which magnet operates a bar 17 via a lever 18 engaging in aslot 19 of the plate 13, as shown in FIGURE 1.

The actuating magnet 16 also serves in the operation of the device forsevering the threads via moving means including a draw bar 21. The drawbar 21 is connected with a lever 22 which can be swung about an axis 23and which carries a thread catcher 24. The thread catcher 24 operatestogether with a cutting blade 26 and aclamiping spring or clip 27 and isguided between these parts. Preferably, the cutting blade 26 and thespring clip 27 are movable relative to the thread severing device orthread catcher 24 and, for this purpose, they have been secured to acarrier 25 that can be swung about the swinging axis 23. The carrier 25is connected with an anchored tension spring 28 and has a stop 29 whichis engageable with a stop portion of the support means 31 for thecutting device.

In the illustration in FIGURE 4, the thread cutting device is in thestarting position. The thread seizing beak or thread catcher 24 liesagainst the carrier 25 of the cutting blade 26 and against the clampingspring or clip 27, and has swung back the carrier 25 from the positionshown in FIGURE 2 and against the pull of the spring 28. If the magnetis now switched on, the thread severing device will swing to positionshown in FIGURE 3. The thread catcher 24 will be disposed with itsseizing beak or catcher hook 32 above the looper blade approximatelywithin the area of the looper point when the magnet 16 has beenenergized. The carrier 25 will have followed the thread catcher 24 underthe influence of the spring 28, until the stop 29 abuts against thesupport 31. At this time the cutting edge 33 of the cutting blade 26will be spaced from the upper edge of the stitch hole the stitch plateat a distance of about a double stitch length. Spring 28 and stop 29cooperate to maintain the cutting blade 26 and clamping spring 27 apredetermined distance from the needle path.

Simultaneously, the thread draw-off parts 11, 12 will have seized theneedle thread 6 and the looper thread 7 and drawn them off by apredetermined length. Preferably, the tension disk spacers 14, 15 willhave moved in simultaneously between the tension discs and have releasedthe thread tension, in order to facilitate the drawing off of thethreads.

If the magnet is now switched off, then the thread catcher 24 swingsback through the path of the needle up to a point which lies on thatside of the path of the needle which faces away from the looper (FIGURE4). At the same time, the seizing beak or catcher hook 32 of the threadcatcher will seize the strand 35 of the looper thread 7 guided from thelooper eye 34 to the last stitch, as well as that strand 36 of theneedle thread 6 extending from the looper blade to the last stitch. Whenthe catcher hook reaches the clamping spring or clip 27 it claimps bothstrands thereagainst and then cuts them off immediately afterwardsagainst the cutting edge 33 of the cutting blade. After the catcher hook32 has been retracted into position between the cutting blade 26 and theclamping spring or clip 27, the thread catcher 24 again engages againstthe carrier 25, and on its path into its end position, it will move saidcarrier with it against the retractile force of the spring 28.

The thread draw-oft parts 11, 12 likewise move back into position forreleasing the necessary quantity of thread which is required to draw outthe threads during swinging back of the thread severing device into itsend position. Simultaneously, the disc spacers 14, 15 retract frombetween the tension discs 8, 9, whereupon said discs will again act onthe threads 6, 7 and clamp the same. Preferably, enough needle thread isdrawn oif so that the latter will be released by the clamping spring orclip 27 just prior to the thread severing device reaching its endposition. Also, enough looper thread will be drawn off so that it willremain held by the clamping spring or clip 27 in its end position. Thus,the looper thread will be held tensed in its position on that side ofthe path of the needle which faces away from the looper. As a result,the needle will enter between the looper blade and the clamped in strandof the looper thread when the machine starts Operating again, so thatthe looper thread upon the return of the looper places itself around theneedle. Thus a faultless stitch formation will be insured. At leastuntil after the formation of the first stitch, the looper thread willremain clamped in and will finally be drawn off from the spring clip 27by the advance of the material through the machine.

The threads are cut olf approximately at a length as shown in FIGURE 5so that the needle thread 6 and the looper thread 7 protrude by about adouble stitch length from the bottom side of the material. Thus, anautomatic unraveling of the seam has been prevented, since the needlethread will prevent a sliding back of the loop of the looper threadthrough the preceding loop of the needle thread. Preferably, however,the drawing olf of looper thread 7 will be adjusted in such a manner,that the looper thread 7 will draw the suspended end of the needlethread 6 toward the preceding needle thread loop and will clamp itthere, as a result of which an increased security is oifered againstunraveling of the seam. See FIGURE 5 Instead of the way shown here,naturally it is also possible that a plurality of needles may cooperatewith the thread guiding looper even though several needle thread loopsmay hang on the looper blade, still they will be grasped by the catcherhook 32 and cut off in the same manner. Besides that, the parts of thecutting-off device may also move in a straight path which runsapproximately tangentially to the are described by the thread catcher inthe embodiment shown.

The control circuit, seen in FIGURE 6, is provided in order to preventthe magnet 16 from being switched on for the operation of the threadsevering device during the sewing, a relay 41 has been provided, whichobtains current only when the sewing machine operates and which opens aswitch 42 in the circuit leading to the magnet 16. In this manner thecircuit to the magnet will be interrupted when the machine is runningand it will not be possible to switch in the magnet 16. If the machinestops, the relay 41 will be deactivated and the switch 42 closes thecontacts in the circuit of the magnet 16. For energizing the magnetthere is provided an additional switch 43 which can be manually operatedat will, which preferably is arranged on the treadle controlling thetransmitter. The switch 43 will be closed, for example, whenever thetreadle is moved opposite to the transmitter engaging position. If atransmitter is used which is adapted for stopping the needle, by choiceeither in high or low position, then an additional switch 44 will beprovided in the circuit to the magnet 16, which, controlled by thetransmitter, will open when the needle is at its lower point and willclose when the needle is in high position.

In order to deenergize the magnet after switching on, and in order toavoid a repeated switching on, an automatic holding relay 45 has beenprovided. In the control circuit leading to the automatic holding relay45, there is a switch 46 which closes the control circuit when the relay41 is energized. As a result of this, the relay 45 is activated andcloses a holding circuit via the holding contacts 47, in which a switch48 has been arranged. Simultaneously, the automatic holding relay 45will bridge contacts in the circuit of the magnet 16 with a switch 49.

If the sewing machine stops and the relay 41 is now deactivated, theswitch 42 is closed and the switch 46 is opened. The automatic holdingrelay 45 remains energized via its holding circuit, so that the switch49 also remains closed. Assuming that the needle is in its high positionand the switch 44 is likewise closed, then the only break in the circuitto the magnet 16 will be the switch 43. If this switch 43 is now closed,the magnet will be energized and will initiate the cutting process.

The magnet when energized will open the switch 48 and thus interrupt theholding circuit to the automatic holding relay 45, which is deactivated.As a result of this,

the switch 49 is opened and the circuit of the magnet 16 is interrupted,as a result of which the magnet 16 is deenergized. It will be apparentthat with this the switch 48 in the holding circuit of the relay 45 isagain closed, since however the switch 47 remains open and the switch 46does not close, before the sewing machine starts to operate again, theswitch 49 also remains open. A renewed closing of the switch 43,therefore, remains without effect. The magnet 16 can be switched onagain only through the switch 43, after the machine has again sewn andafter the automatic holding relay 45 has been energized via the relay41. This insurance against repeated cutting is necessary in order toassure that the clamping spring or clip 27 will not release the looperthread before at least one stitch has been sewn.

In the embodiment shown in FIGURES 7 and 8 parts corresponding to partsshown in FIGURES 3 and 4 have like reference characters applied thereonwith the addition of an exponent whereas modified parts have distinctreference characters applied thereon.

In this modified showing the thread catcher 24 carries two threadseizing beaks or catcher hooks 52 and 53, both of which coact with thecutting blade 26*. The spring clip 27 has a notch 54 formed therein(FIGURE 8). If the thread catcher 24 is swung in (FIGURE 7), then thecatcher hook 52 will move beyond the strand of the looper thread 7 inthe direction of the looper point 4*, while the hook 53 is in a swung inposition between the loop of the needle thread 6 hanging on the looperand the strand of the looper thread 7 leading to the last stitch. If thethread catcher 24 swings back into its starting position, then the hook52 will grasp the looper thread, while the hook 53 will seize the strandof the needle thread loop running from the looper blade to the laststitch. Both threads will thus be cut off against the cutting blade 26but only the looper thread 7 will be clamped in between the catcher hook52 and the clamping spring or clip 27 The catcher hook 53, in the end orstarting position, is in the area of the notch 54 of the spring clip 27as a result of which the needle thread is released, or in other words,will not be clamped.

The same effect can be achieved if the catcher hooks are displacedlaterally in relation to one another in their direction of movement andif the spring clip merely covers the path of movement of the catcherhook 52. As a result of this, the catcher hook 53 would not engage withthe clamping spring or clip 27, and thus the needle thread likewisewould not be clamped.

Besides, the clamping of the needle thread can be avoided in that thecatcher hook 53 is formed with a recess at the bottom side as comparedto the catcher hook 52 and thus, in the end or starting position isdisposed at a distance from the spring clip 27, or in that the catcherhook 53 is formed with a cutting blade on which the needle thread willbe broken, before the catcher hook 53 reaches the spring clip 27.

Finally, it is also possible that the catcher hook 53 may be arranged onthe spring clip 27. In this case the clamping spring or clip 27 togetherwith the thread catcher 24 swings into position in which the catcherhook 53 will be between the needle thread loop and the looper thread. Onswinging back, the thread catcher 24 of the spring clip 27 will be inadvance and clamp the looper thread 7 between the catcher hook 52 andthe catcher hook 53, which is located on the spring clip, whereupon bothelements will swing back together and both threads 6*, 7 will be cut ofiagainst the cutting blade 26*". In this case, too, the needle thread 6is not clamped in.

While preferred embodiments of the invention are disclosed herein, it isto be understood that other specific arrangements of the parts may beprovided within the scope of the invention as defined in the appendedclaims.

I claim:

1. A thread severing device for cutting threads on a double chain stitchsewing machine of the type including a needle plate, a reciprocatingneedle and a thread carrying looper spaced from said needle plate in thedirection of needle reciprocation, said thread severing devicecomprising cutter means movable to a first point where thread cutting isto be eifected, and thread catching means movable with said cutter meansto said first point, said catching means movable to a second point forcatching the thread and moving the thread from said second point to saidfirst point for thread cutting cooperation with said cutter means atsaid first point.

2. A thread severing device according to claim 1 further includingmovable clamping means and means for moving said cutter means andclamping means to said first point at a predetermined distance from thepath of said needle and maintaining said cutter and clamping means atsaid first point during the timev said thread catching means moves toand from said second point, said means for moving said cutter andclamping means moving said thread catching means into thread cuttingcooperation with said cutter means at said first point.

3. A thread severing device according to claim 1 comprising actuatingmeans for actuating said thread catching means, and control meansincluding interruption means for precluding operation of said actuatingmeans while the sewing machine is running and for preventing repeatedoperation of actuating means once the sewing machine has stoppedrunning.

4. A thread severing device for cutting threads on a double chain stitchsewing machine of the type including a needle plate, a reciprocatingneedle and a thread carrying looper spaced from said needle plate in thedirection of needle reciprocation, said thread severing devicecomprising cutter means for cutting a thread, clamping means, threadcatching means movably mounted between said clamping means and saidcutter means and moving means for first moving said thread catchingmeans into thread engaging position and then moving said thread catchingmeans into cooperation with said cutter means and said clamping means toeffect thread cutting at one side of said catching means and to effectthread clamping against a further side of said catching means.

5. A thread severing device according to claim 4 wherein said threadcatching means comprises a cutting edge and said cutter means comprisesa cutter blade, said cutting edge being positioned to move in threadcutting relation with said cutter blade when said catching means ismoved into thread cutting cooperation with said cutter means.

6. A thread severing device according to claim 4 wherein said threadcatching means comprises a catcher hook and said clamping meanscomprises a spring clip positioned to press against the underface ofsaid catcher hook when said catching means is moved into thread cuttingcooperation with said cutter means.

7. A thread severing device according to claim 4 wherein said clampingmeans is adapted to clamp a looper carried thread against said catchingmeans on the opposite side of the needle path from said thread carryinglooper.

8. A thread severing device for cutting threads on a double chain stitchsewing machine of the type including a needle plate, a reciprocatingneedle and a thread carrying looper spaced from said needle plate in thedirection of needle reciprocation, said thread severing devicecomprising cutter means for cutting a thread, thread clamping means,thread catching means movably mounted between said clamping means andsaid cutter means, carrier means for carrying the cutter means andclamping means, said carrier means and thread catcher means mounted forswinging movement about a common axis, and moving means for first movingsaid thread catching means into thread engaging position and then movingsaid thread catching means into thread cutting cooperation with saidcutter means.

9. A thread severing device according to claim 8 further includingbiasing means and stop means, said biasing means biasing said carriermeans toward said stop means.

10. A thread severing device according to claim 9 wherein said catchingmeans contacts said carrier means to maintain said thread catchingmeans, cutter means and clamping means in an end position when saidmoving means is unactuated.

11. A thread severing device for cutting threads on a double chainstitch sewing machine of the type including a needle plate, areciprocating needle and a thread carrying looper spaced from saidneedle plate in the direction of needle reciprocation, said threadsevering device comprising cutter means for cutting a thread, clampingmeans, thread catching means movably mounted between said clamping meansand said cutter means and comprising first catcher hook means forcatching the needle thread and second catcher hook means -for catchingthe looper thread, and moving means for first moving said threadcatching means into thread engaging position and then moving said threadcatching means into thread cutting cooperation with said cutter means.

12. A thread severing device according to claim 11 wherein said firstcatcher hook is spaced from said second catcher hook in the direction ofmovement of the catching means, whereby said first catcher hook isadapted to extend between the looper thread and the needle thread whensaid thread catching means is in its thread engaging position.

13. A thread severing device according to claim 11 wherein said secondcatcher hook is positioned to cooperate with said clamping means formaintaining a looper thread in clamped condition and said first catcherhook is positioned to release a needle thread when said thread catchermeans has moved from said thread engaging position.

14. A thread severing device according to claim 11 wherein said clampingmeans comprises a spring clip having a notch formed therein, said notchbeing adjacent said first hook when said catcher means has been movedfrom thread engaging position whereby said notch plrecludes clamping ofsaid needle thread by said spring c 1p.

15. A thread severing device according to claim 11 wherein said firstand second hooks are disposed laterally with respect to the direction ofmovement of said catching means and said clamping means is positioned tocooperate with said second hook only to clamp only the looper carriedthread.

16. A thread severing device according to claim 11 wherein the surfaceof said first hook facing the clamp ing means recedes relative to thecorresponding surface on said second hook, said clamping means clamping51ml the looper thread to the surface of said second 17. A threadsevering device according to claim 11 18. A thread severing device forcutting threads on a double chain stitch sewing machine of the typeincluding a needle plate, a reciprocating needle and a thread carryinglooper spaced from said needle plate in the direction of needlereciprocation, said thread severing device comprising cutter means forcutting a thread, thread catching means, moving means for first movingsaid thread catching means into thread engaging position and then movingsaid thread catching means into thread cutting cooperation with saidcutter means, thread draw-otf means, and actuating means includingelectromagnetic means for simultaneously actuating said thread catchingmeans and said thread draw-off means.

19. A thread severing device according to claim 18 further comprisingthread tensioning means, said thread draw-off means comprising means fordeactivating said thread tensioning means.

20. A thread severing device for cutting threads on a double chainstitch sewing machine of the type including a needle plate, areciprocating needle and a thread carrying looper spaced from saidneedle plate in the direction of needle reciprocation, said threadsevering device comprising cutter means for cutting a thread, threadcatching means, and moving means for first moving said thread catchingmeans into thread engaging position and then moving said thread catchingmeans into thread cutting cooperation with said cutter means, actuatingmeans including electro-magnetic means for actuating said threadcatching means and control means including interruption means forprecluding operation of said actuating means while the sewing machine isrunning and for preventing repeated operation of said actuating meansonce the sewing machine has stopped running, said interruption meansincluding a first switch in series connection with a second manuallyoperable switch, and an automatic holding relay connected to said firstswitch for closing of said first switch upon energization of said relay.

21. A thread severing device according to claim 20 for said holdingrelay including a third switch connected to said electromagnetic meansfor opening upon energization of said electromagnetic means.

22. A thread severing device according to claim 21 wherein said controlmeans comprises a control circuit for said holding relay including afourth switch connected to a second relay, said fourth switch beingadapted to be closed upon energization of said second relay duringoperation of the sewing machine.

23. A thread severing device according to claim 22 wherein said controlmeans comprises a fifth switch connected to said second relay, saidfifth switch being adapted to be opened upon energization of said secondrelay during operation of the sewing machine.

References Cited UNITED STATES PATENTS 1,395,274 11/ 1921 Hagelstein112252 2,335,827 11/1943 Gunther 112252 3,211,117 10/1965 Speichermannet al. 112252 1,234,258 7/1917 Barron 112252 1,883,654 10/1932 Ericsson112-252 wherein said control means comprises a holding circuit 25HERBERT F. ROSS, Primary Examiner.

